This manual covers the Yanmar Marine Diesel Engine series, specifically the 4LHA-STE, 4LHA-STZE, 4LHA-STP, 4LHA-STZP, 4LHA-DTE, 4LHA-DTZE, 4LHA-DTP, 4LHA-DTZP, 4LHA-HTE, 4LHA-HTZE, 4LHA-HTP, and 4LHA-HTZP models. These engines are engineered for robust marine applications, offering reliable performance and durability. The series is known for its efficient power delivery and advanced fuel injection systems, making it a preferred choice for various marine vessels. This workshop service manual provides comprehensive guidance for the maintenance, repair, and troubleshooting of your Yanmar marine diesel engine. It includes detailed procedures for engine disassembly and reassembly, fuel injection equipment, intake and exhaust systems, lubrication, cooling, and electrical systems. Information on reduction and reversing gears, as well as optional remote control systems, is also covered. This manual is an essential resource for owners, technicians, and mechanics to ensure optimal engine performance and longevity.